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Finding the Fourth Proportional to 31.48, 47.20 and 12.20

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Solution

The fourth proportional to 31.48, 47.20 and 12.20 is: 18.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.48 : 47.20 = 12.20 : x
  2. Step 2: Convert to fraction form
    31.48/47.20 = 12.20/x
  3. Step 3: Cross multiply
    31.48x = 47.20 × 12.20
  4. Step 4: Simplify right side
    31.48x = 575.93
  5. Step 5: Solve for x
    x = 575.93/31.48
  6. Step 6: Final answer
    x = 18.30

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.